Replies

1. 
   dgreen | May 03, 2007 03:47am | #1

   Did you check the piston rings?

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   It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore

2. 
   EdHarrow | May 03, 2007 05:50am | #2

   A little bit of oil or a lotta bit of oil?  Any (ok, most) oil-sealed compressors will tend to dump oil out their exhaust, that's why compressors are often fitted with a trap (also for water, of course).

3. 
   melonhead | May 03, 2007 07:33am | #3

   Hi Lou:

   If the compresssor is older  or has not been well maintained  the rings are probably passing a bit of oil which is ending up in the air line. This is not the end of the world or the end of your compressor. Unlike  a car engine , worn rings in a compressor only minimally efect the performance of the compressor.

   There are a few things that you can do about it . First , if your  compressor is a central air source for a large shop , you need to de-grease (or oil) your plumbing.  If it is only hooked up to  tools , blow guns etc. by a single hose , it might be best to replace the hose, but if hard plumbed, here is what I have found to be effective :

   Disconnect the air plumbing from the compressor end. Then go to the farthest down stream from the compressor and disconnect the air line from that station. Hook up the  compressor end of the plumbing to your shop-vac ( wet mode ) and suction up a quart or two of  a solution fo hot water with dish washer soap ( Cascade or substitute ) through the plumbing from the farthest downstream station.

   Once this is done , make sure that the moisture in the compressor tank ( which is likely to be mixed with oil) has been purged thouroughly. If necessary let the compressor pump all the way up until it stops and use the tank purge valve ( generally found on the lowest point of the tank bottom) to blow out all of the air , which will cary the moisture and oil with it. Do this repeatedly until there is the least possible oil/water discharge mixed with the air. Next, before you hook the plumbing back to the compressor , buy a coalescing filter and connect it  between the compressor and the air line. These filters have a filter element that has an afinity for oil, even in the vapor state . The oil " coalesces " on the filter element and gravity pulls it to the bottom of the filter bowl . If you 'splurge' you can get a filter with an automattic drain , or you can drain it manually. The filter element should be changed anually  if you use the compressor moderately to heavily.

   I have been working on air compressors used by dentists for nearly forty years , and this has become a 'serious' problem since the advent of tooth colored composite fillings. A relatively small amount of oil vapor can cause a composite filling to fail ( i.e., fall out). The coalescing filter vastly improves the results of all but the worst oil problems.

   Hope this helps,

   Bill

   PS : This is a decent coalescing filter -- http://www.grainger .com . Search for Item # 6B261

    

    

   
   

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   Edited 5/3/2007 12:37 am ET by melonhead

1. 
   loucarabasi | May 03, 2007 11:38am | #4

   Thanks Bill, I will do what you said. I did replace the rings too with the rebuild kit.

   Thanks again, Lou

1. 
   JerryPacMan | May 03, 2007 04:22pm | #5

   Did you run the compressor 1 hour with no load, drain open, to seat the new rings? 

   Life is what happens to you when you're making other plans .

4. 
   RickChristopherson | May 04, 2007 01:37am | #6

   Before you tear your compressor apart again, you may want to rethink what you think is coming out of the lines.

   It's not oil! It is dirty water, and it is because you have not fully drained your compressor in a long time. Think about it, if your crankcase was spitting out enough oil to be noticeable at the hose, it would be completely empty within the week.

   Also, oil will not remain vaporized in the tank like water will, so it will never make it into the tank outlet, which is toward the top of the tank.
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   Even though you may regulary drain the liquid from your tank, you need to periodically drain the entire tank and start fresh, especially in the humid summer months.

   The humidity in the tank when it is in use and cycling will be super-saturated, which means that it will be greater than 100% RH. Simply draining off the liquid from the bottom of the tank will not remove this condition. You need to periodically drain all of the air from the tank.